4 ms·

"The proper way"? Not only is it less familiar than the usual "i = 0; i < n; i++" idiom, requiring the reader to examine exactly what it's doing, but now i goes

by Rangi42 13y ago

"The proper way"? Not only is it less familiar than the usual "i = 0; i < n; i++" idiom, requiring the reader to examine exactly what it's doing, but now i goes from n to 1 instead of 0 to n-1. What's so bad about caching the strlen result in a variable beforehand?

tedunangst 13y ago
You have read his loop wrong. It has the same bounds.
nitrogen 13y ago
i goes from n-1 to 0 in the example because for loops execute the condition before the first iteration.
goldenkey 13y ago
You're wrong. Maybe I should hire my next team based on loop analysis ;-) http://codepad.org/kd3oOBAb http://codepad.org/kd3oOBAb
- vidarh 13y ago
  And I think this perfectly demonstrates why it is a stupid approach to take in the first place. In fact, personally I have a tendency to avoid for-loops in C because of the awful syntax; I much prefer using while-loops as I find them far clearer. In 25+ years of C, I've seen plenty of people getting for-loops wrong (making broken assumptions about what's evaluated where, and countless off by one bugs), but everyone gets while-loops. If you are going to do for-loops in C, stick with the most obvious, simplest variants possible - the moment you try to be smart, you've substantially increased the odds that a maintenance programmer will introduce a bug at one point or another.
  - nitrogen 13y ago
    For the sake of job security, I propose using the comma operator to put the entire loop body within the for() parentheses, and replace the block with a semicolon: // Pure C99 (prints an invalid character at the end) for( FILE *f = fopen("/etc/fstab", "r"); !feof(f) || (fclose(f), 0); putchar(fgetc(f)) ) ; // C99+POSIX for( int fd = open("/etc/fstab", O_RDONLY), c = 0; read(fd, &c, 1) || (close(fd), 0); write(1, &c, 1) ) ;
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by Rangi42 13y ago

tedunangst 13y ago

You have read his loop wrong. It has the same bounds.

nitrogen 13y ago

i goes from n-1 to 0 in the example because for loops execute the condition before the first iteration.

goldenkey 13y ago

You're wrong. Maybe I should hire my next team based on loop analysis ;-) http://codepad.org/kd3oOBAb http://codepad.org/kd3oOBAb

vidarh 13y ago
And I think this perfectly demonstrates why it is a stupid approach to take in the first place. In fact, personally I have a tendency to avoid for-loops in C because of the awful syntax; I much prefer using while-loops as I find them far clearer. In 25+ years of C, I've seen plenty of people getting for-loops wrong (making broken assumptions about what's evaluated where, and countless off by one bugs), but everyone gets while-loops. If you are going to do for-loops in C, stick with the most obvious, simplest variants possible - the moment you try to be smart, you've substantially increased the odds that a maintenance programmer will introduce a bug at one point or another.
- nitrogen 13y ago
  For the sake of job security, I propose using the comma operator to put the entire loop body within the for() parentheses, and replace the block with a semicolon: // Pure C99 (prints an invalid character at the end) for( FILE *f = fopen("/etc/fstab", "r"); !feof(f) || (fclose(f), 0); putchar(fgetc(f)) ) ; // C99+POSIX for( int fd = open("/etc/fstab", O_RDONLY), c = 0; read(fd, &c, 1) || (close(fd), 0); write(1, &c, 1) ) ;

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